Methods for discharging fluent substances into well bores



March 18, 1969 w. T. BELL 3,433,305

METHODS FOR DISCHARGING FLUENT SUBSTANCES INTO WELL BORES Filed NOV. 6, 1967 Sheet f of 5 BMM@ March 18, 1969 Filed Nov.

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I I w35 g" A; f W//a/? 7.- .5@// INVENTOR.

l ii i BY l E y r I L^ 4770/? y March 18, 1969 w, T, BELL 3,433,305

METHODS FOR DISCHARGING FLUENT sUBsTANCEs INTO WELL BoREs Filed Nov. 6, 1967 SheetI j of5 VV////c7m 7.' .5e//

INVENTOR.

MKM

United States 3,433,305 METHODS FOR DISCHARGING FLUENT SUBSTANCES INTO WELL BORES William T. Bell, Houston, Tex., assignor to Schlumberger Technology Corporation, Houston, Tex., a corporation f Texas Filed Nov. 6, 1967, Ser. No. 680,648 U.S. Cl. 166-297 Int. Cl. E21b 43/11, 33/13 4 Claims ABSTRACT 0F THE DISCLOSURE It is widely recognized that the entrance 'of well control fluids or so-called mud into newly-formed perforations into an earth formation may, in time, plug the perforations so tightly that subsequent production of oil and/or gas from the formation will at least be impaired if not halted altogether. To counter this damage, suitable oilsoluble liquids and the like are commonly injected into the well bore at least in the vicinity of where perforations are to be made and a perforator is then actuated while these protective liquids are hopefully still in place. In this manner, it is believed that the soluble protective liquids will immediately rush into the perforations as they are made and block the subsequent entry of the well control fluids. Then, when connate fluids are produced through perforations protected in this manner, the produced fluids can easily flow into the well bore and wash away the soluble protective liquids.

Various proposals have been made heretofore for injecting such protective liquids around a perforator just before it is actuated to produce perforations at a desired location in a well bore. For one reason or another, however, these proposed techniques and devices have not been commercially accepted by the industry. For example, one tool proposed heretofore employs a self-contained pump that will supposedly pump a limited supply of protective liquids into the annulus around the perforator and completely displace the well control fluids in this space up above an inflated packer on the tool. A similar proposed tool is arranged to employ a source of high-pressure gas for discharging protective liquids around the perforator to displace the well control fluids upwardly away from the perforator.

It will be appreciated, however, that for the latter one of these tools to accomplish its intended function, the protective liquids must displace a signicant volume of the Well control fluids against the extreme hydrostatic pressure typically encountered in Well bores. Moreover, with either of these techniques, there is no assurance that the protective liquids will not be discharged at such a rate that they will merely diffuse into the surrounding Well control fluids rather than enveloping the perforator in a substantially homogeneous mass of the protective agent that will remain in position until the perforator is actuated. Similar problems are also encountered where it is desired to perforate a formation interval and then inject a treating agent, such as acid or the like, to clean the perforations.

atent "ice Accordingly, it is an object of the present invention to provide new and improved methods for reliably discharging a homogeneous mass of selected fluent substances around a well perforator and then perforating an interval of a Well bore traversing this mass of fluent substances so that the selected substances will enter the resulting perforations rather than being diluted by or being dispersed through other fluids in the well bore.

This and other objects of the present invention are accomplished by positioning a tool including a perforator adjacent to a formation interval to be completed. As the perforator is moved into alignment with the formation, fluids in the well bore are removed from the space to be occupied by the perforator and simultaneously replaced with a fluent treating substance. Thus, upon actuation of the perforator, the treating substance will enter the resulting perforations without interference from the displaced well bore fluids. Various embodiments are shown of tools which, in response to movement of the supporting member, will displace the well bore fluids and discharge a suitable treating agent into the resulting voided space at a rate corresponding to the movement of the suspension member.

The novel features of the present invention are set forth with p'articularity in the appended claims. The operation, together with further objects and advantages thereof, may best be understood by way of illustration and example of certain procedures when taken in conjunction with the accompanying drawings, in which:

FIGURES l-3 depict the successive steps of one manner in practicing the methods of the present invention;

FIGURES 4A and 4B are cross-sectional views of a portion of a preferred embodiment of a completion tool adapted for performing the methods of the present invention;

FIGURE 5 is a cross-sectional view taken along the lines 5 5 in FIGURE 4B;

FIGURES 6A and 6B are views similar to FIGURES 4A and 4B but showing various elements thereof in their nal position;

FIGURE 7 is a schematic representation of an alternative tool for practicing the present invention;

FIGURE 8 is an elevational cross-sectioned View of a portion of the completion tool shown in FIGURE 7; and

FIGURE 9 is a schematic view of still another completion tool for practicing the present invention.

Turning now to FIGURES 1-3, a well-completion tool 10 is shown as it might appear while performing the methods of the present invention in a typical well bore 11. As is customary, the well bore 11 has a string of casing 12 secured therein by cement 13, with the casing eX- tending through an earth formation 14 from which oil or gas is to be produced. A conventional well control fluid or so-called mud 15 is disposed in the casing 12 in the usual manner.

The completion tool 10 is supported from a typical suspension cable 16 that includes one or more electrical conductors (not shown) and is spooled in the usual manner on a winch (not shown) at the surface. To practice the methods of the present invention, the tool 10 must include fluid-displacement means such as a reservoir 17 containing a supply of a selected fluent substance such as, for example, a temporary plugging agent 18 that is to be selectively discharged for isolating perforations in the producing formation 14 from the mud 15 in response to movement of the tool through the well bore 11 over a span of travel that at least includes the interval of the formation to be perforated.

To accomplish this expulsion of the treating agent 18 as the completion tool 10 is traversed through the well bore 11, the fluid-displacement means further include means such as a piston 19 that is initially positioned in the upper portion of the reservoir 17 and fluidly sealed for sliding movement in relation to the inner walls thereof and a ow diverter 20 that is mounted around the outside of the reservoir between longitudinally spaced ports 21 and 22 respectively in communication with the spaces 23 and 24 in the reservoir above and below the piston. A typical well perforator 25 supported below the reservoir 18 and having one or more perforating devices, such as shaped charges 26, adapted for selective actuation from the surface completes the well tool 10. It is preferred to also include means, such as a typical casing-collar locator 27 mounted on the tool 10, for providing indications at the surface from which the position of the completion tool in relation to the formation 14 can be established with reasonable accuracy. A casing-collar locator such as that shown in Patent No. 3,114,876 will, of course, be capable of accomplishing this.

Accordingly, as shown in FIGURE 1, in one manner of practicing the present invention, with the aid of the collar locator 27, the completion tool is brought to a position below the formation 14. It will be appreciated, of course, that provisions must be made to prevent premature discharge of the iluent treating agent 18 as the tool 10 is being moved through the well bore 11 to the position depicted in FIGURE 1. Thus, depending upon the particular arrangement of the completion tool 10, the tool is selectively enabled from the surface so that subsequent travel of the tool will expel the uent treating substance 18 at a controlled rate from reservoir 17.

Once the tool 10 has been enabled, the suspension cable 16 is moved to raise the completion tool in the direction indicated by the arrow 28 in FIGURE 2. It will be recognized that since the diverter 20 blocks most, if not all, of the annular clearance space between the tool 10 and the casing 12, upward movement of the tool will be eiective to displace a volume of the control tluids that is directly related to the distance the completion tool is moved. Accordingly, as the completion tool 10 is moved upwardly, the control fluids 15 entering the upper reservoir space 23 by Way of the ports 21 are effective in moving the piston 19 downwardly in relation to the reservoir 1'7. It will be appreciated, therefore, that as the piston 19 is moved downwardly, the treating agent 18 will be exhausted from the lower reservoir space 24 through the lower ports 22 and into the annulus between the tool 10 and the casing 12. The volume of the treating agent 18 that is exhausted, as at 29, will, of course, be equal to the volume of the control iluids 15 entering the upper reservoir space 23. Thus, the volume of uent treating agent 18 discharged will be directly related to the distance the tool 10 is moved and the treating agent will be expelled at a rate corresponding to the speed at which the tool is moved.

0f particular significance, it will be noted that since the uent substance 18 is discharged into the annulus below the diverter as the well control uids 15 formerly occupying that same clearance space are entering the upper reservoir space 23, the discharged treating agent 29 will till this annular clearance space rather than being diffused into the control fluids as has been the case heretofore. This will, of course, result in a more complete envelopment of a homogeneous mass of the fluent substance in that interval of the well bore 11 that is to be perforated. Moreover, the diverter 20 will prevent the well control fluids 15 above the diverter from settling into the discharged treating agent 29. Since the treating substance has been selected to have a lower density than that of the well control lluids 15, there Will be little or no tendency for the well control fluids 15 below the diverter 20 to dilute the discharged treating agent 29. Thus, the present invention insures that the treating agent 29 will compleely ll the annulus below the diverter 20 in a more consistent manner than has been possible heretofore.

As seen in FIGURE 3, as the tool 10 is moved further upwardly, the perforator is brought into the blanket of discharged treating substance 29 opposite the formation 14. Then, once it is established that the perforator 25 is correctly positioned, it is actuated to detonate the shaped charges 26 and produce a corresponding number of perforations 30 through the casing 12 and the cement sheath 13 into the earth formation 14. Thus, once the perforations 30 are produced, they will be immediately lled by the discharged treating agent 29. This will, of course, prevent subsequent entry of the well control uids 15 into the perforations 30 after the tool 10 is removed from the well bore 11. Accordingly, it will be appreciated that the practice of the present invention will be effective to provide a homogeneous mass of the selected fluent substance 18 completely enveloping the perforator 25 thereby insuring that only the treating agent can enter the perforations 30 once they are produced.

It will be appreciated, of course, that various arrangements of apparatus can be provided to practice the present invention. The central portion of an exemplary tool 50 for practicing the present invention is shown in FIGURES lA-4B. As seen there, the tool 50 is comprised of an elongated housing 51 having an adapter head 52 connected at its upper end and adapted for coupling the housing to other tools (not shown) thereabove such as a typical centralizer and a casing-collar locator. Similarly, the lower end of the housing 51 is suitably adapted for connection to another tool centralizer (not shown) and a perforator (not shown). This perforator (not shown) may, of course, be any one of the various types of perforators customarily employed in well-perforating operations. Although it is customary to fabricate well tools in a number of separable sections for ease of manufacture and assembly, various portions of the tool 50 are shown in the drawings as being integral with other portions so that minor constructional details of the tool will not affect an understanding of the invention.

In addition to the perforator (not shown), the tool 50 includes a reservoir 53 adapted to carry a supply of a suitable fluent substance, a selectively-operable flow diverter 54 adapted to displace the substance from 'the reservoir once the diverter is enabled and as the tool is moved through a well bore, and a control section 55 for selectively enabling the diverter and perforator rupon command from the surface. The inter-relatoin of jthese various elements 5355 and the perforator will subsequently become more apparent.

The reservoir 53 in the upper portion of the housing '.51 is formed by an enlarged longitudinal bore 56 of uniform diameter extending an appropriate distince between the upper adapter head 52 and the upwardly- .facing shoulder 57 formed by the junction of the enlarge bore and a smaller coincidental bore 58 extending downwardly from thereon through the housing to a termination somewhat above the lower end of the housing. A tubular conduit 59 is depending secured and tluently sealed to the adapter head 52 and extended downwardly along 'the central axis of the reservoir 53 to a position at least adjacent to the shoulder 57 for enclosing an electrical conductor 60. 'The electrical conductor 60 is passed through a typical uid seal 61 in the adapter head 52 and extended on upwardly through the tool 50 for connection to conductors enclosed in a suspension cable (not shown).

An annular piston member 62 is slidably disposed in the enlarged bore 56 and uidly sealed therein lby an external sealing member 63 engaging the housing 51 and an internal sealing member 64 engaging the conduit 59 to define upper and lower enclosed spaces 65 and 66 in the reservoir 53. In its initial position shown in FIGURE 4A, the piston member 62 is located as near as possible to the adapter head 52 to enable the lower enclosed space 66 of the reservoir 53 to receive a maximum quantity of a treating agent (not shown). One or more lateral ports 67 (FIGURE 4A) are provided in the upper portion of the housing 51 to admit well control fluids into the upper enclosed space 65 of the reservoir 53 as the tool 50 is used in practicing the methods of the present invention. Similarly, one or more normally-closed ports 68 (FIGURE 4B) are provided in the lower portion of the housing 52 and adapted, when open, for discharging a fluent substance from the lower enclosed space 66 of the reservoir 53. Accordingly, as will subsequently be explained, once the lower ports 68 are opened and the tool 50 is operated so as to admit a ow of well control uids into the upper ports 67, the piston 62 will move downwardly in the reservoir 53 and displace a corresponding volume of the treating agent from the lower space 66 through the lower ports as the well control fluids enter the upper ports and fill the upper space 65.

To facilitate the movement of the tool 50 through a uid-lilled well bore to a starting position, the diverter 54 is initially retracted to provide sutcient clearance therearound between the housing 51 and the internal wall of the well casing (not shown). Similarly, although the piston 62 will normally tend to remain in its elevated position shown in FIGURE 4A so long as the diverter 54 is retracted, it is preferred to keep the ports 68 closed so that the uent substance will not be lost from the lower space 66. It will be appreciated, therefore, that means must be provided to selectively extend the diverter 54 as well as open the ports 68 upon command from the surface.

Accordingly, as shown in FIGURE 4B, the diverter 54 is preferably comprised of a exible sleeve 69 of an elastomeric material that is secured at its upper end around the central portion of the housing 51. The outer diameter of the housing 51 is reduced just below the upper end of the elastomeric sleeve 69 and appropriately formed to provide longitudinally-spaced external surfaces 70 and 71 of equal diameter that are separated from one another by an external surface 72 of a more-reduced diameter. An elongated sleeve member 73 having an enlarged-diameter upper portion 74 is slidably mounted around the reduced central portion of the housing 51 and uidly sealed thereto by sealing members 7S and 76 respectively encircling the spaced external surfaces 70 and 71. The elastomeric sleeve 69 is disposed around a plurality of longitudinally-extending, outwardly-bowed iiexible strips 77 that are circumferentially spaced around the housing 51 and have their upper and lower ends secured between opposed shoulders 78 and 79 on the housing and enlarged portion 74 of the slidable sleeve members 73 respectively. The lower end of the elastomeric sleeve 69 is carried below the lower end of the bowed spring strips 77 and secured around the enlarged sleeve portion 74. To insure that the spring strips 77 will remain in the outwardly-bowed position shown in FIGURE 4B, the enlarged portion 74 of the slidable sleeve member 73 is extended upwardly to about the middle of the spring strips and progressively enlarged so as to engage the rear surface of each strip and keep the central portion of the strips bowed outwardly.

It will be appreciated, therefore, that so long as the slidable sleeve member 73 remains in the position illustrated in FIGURE 4B, the elastomeric sleeve 69 will retain its generally relaxed position. By moving the slidable sleeve 73 upwardly in relation to the housing 51, however, the sleeve shoulder 79 is moved toward the housing shoulder 78 to shorten the distance between the opposite ends of the spring strips 77 and cause their central portions to bow radially outwardly. Thus, as the slidable sleeve member 73 is moved upwardly, the outward movement of the midportions of the spring strips 77 will radially expand the central portion of the elastomeric sleeve 69 a corresponding distance. Conversely, by returning the sleeve member 73 downwardly, the spring strips 77 will relax and restore the elastomeric sleeve 69 to its original position.

Accordingly, it will be recognized that by releasably securing the slidable sleeve 73 in the position shown in FIGURE 4B, the diverter sleeve 69 will be maintained in its fully-retracted position and the tool 50 can be readily moved in a well bore with the well fluids therein freely bypassing the tool through the annular clearance around the diverter 54. To releasably secure the sleeve 73, the control section 55 includes latch means such as are provided by one or more ball members 80 that are loosely confined in lateral openings 81 spaced around the lower portion of the slidable sleeve and adapted to be partially retained in a peripheral groove 82 around the housing 51 by a second sleeve member 83 that is telescoped over the slidable sleeve and releasably coupled to the housing 51.

An inwardly-projecting lug 84 on the retaining sleeve 83 is normally engaged with a dog 85 disposed in a housing recess 86 below the retaining sleeve and pivotally mounted therein on a shaft 87 journalled to the housing 51. To retain the pivoted dog in engagement with the lug 84, the control section 55 further includes a selectively-operable release such as an electrically-responsive detonator or so-called explosive squib 88 that is adapted for abutting engagement with the dog to prevent it from rotating into a non-abutting position. Biasing means, such as a compression spring 89 arranged between opposed shoulders on the sleeves 73 and 83, are provided to urge the retaining sleeve upwardly in relation to the slidable sleeve member once the explosive squib 88 has freed the dog 85 for rotation.

Accordingly, once the retaining sleeve 83 is allowed to move upwardly in relation to the slidable sleeve 73, a diametrical enlargement within the retaining sleeve, such as provided by longitudinal grooves or slots 90 that are respectively longitudinally aligned with the balls 80, is moved into juxtaposition with the retaining balls. It will be appreciated, therefore, that by appropriately sizing the retaining balls 8U in relation to the annular clearances between the inner surface of the peripheral groove 82 and the inner surface of the sleeve 83 on the one hand and the inner surface of the slots 90 on the other hand, the balls cannot be freed from the peripheral groove until the retainer sleeve has moved upwardly to bring the slots into registration with the balls.

By extending the retainer sleeve 83 upwardly and uidly sealing it around the slidable sleeve 73 by sealing members 91 and 92 spaced above and below one or more ports 93 in the slidable sleeve and approximately in registration with the lower housing ports 68, the retainer sleeve also serves as a valve that selectively blocks the ow of a treating agent from the lower space 66 until the squib 88 is detonated and the diverter 54 is extended. Once, however, the squib 88 is detonated and the retainer sleeve 83 is moved upwardly relative to the slidable sleeve 73 by the spring 89, lateral ports 94 in the retainer sleeve are brought into registration with the housing ports 68 and ports 93 in the slidable sleeve to allow the treating agent to be exhausted therethrough as the piston `62 moves downwardly.

From the description of the tool 50 to this point, it will be seen that once all of the various elements described so far are in their respective positions depicted in FIG- URES 4A and 4B, the diverter 54 will be retained in its retracted position so long as the explosive squib 88 is not detonated. When the squib 88 in the control section 5S is detonated, the spring 89 will urge the retainer sleeve 83 upwardly in relation to the slidable sleeve 73 which, at this time, is still secured to the housing 51 by the retainer balls 80. Once, however, the retainer sleeve 83 moves a suflicient distance upwardly to bring the slots 90 into registration with the outer surfaces of the balls 80, the combined force of a compression spring 95 carried between opposed shoulders on the slidable sleeve 73 and the housing 51 and another compression spring 96 will cause the balls to be cammed out of the circumferential groove 82 and into the enlarged annular space between the outer surface of the housing 51 and the inner surfaces of the slots 90. The spring 96 is engaged between a fixed shoulder 97 on the sliding sleeve 73 and an abutment 98 releasably secured at this time to the housing 51. The function of this movable abutment 98 and the manner of securing it will be subsequently explained.

Accordingly, it will be appreciated that once the balls 80 are released from the circumferential groove 82, the sliding sleeve 7 3 will be shifted upwardly by the combined force of the springs 95 and 96 to begin bowing the spring strips 77 outwardly. The retainer sleeve 83 is, of course, carried further upwardly by the sliding sleeve 73. It will be recognized, therefore, that the spring 89 will move the retainer sleeve 83 upwardly in relation to the sliding sleeve 73 to a position where the ports 93 and 94 are in registration with one another. Thus, once the sliding sleeve 73 reaches its elevated position, the sleeve ports 93 and 94 will be in registration with the housing ports 68. At this point, the bowed spring strips 77 will have been expanded outwardly a suicient distance to bring the elastomeric sleeve 69 either very near to or into engagement with the inner wall of the casing. This will, therefore, block the annular space between the tool 50 and the casing.

Once the diverter 54 is fully expanded and the ports 68 opened, it will be appreciated that upward movement of the tool 50 will force the well bore fiuids through the ports 67 at the upper end of the housing 51 and into the upper enclosed space 65 therein. Thus, continued upward movement of the tool 50 will be effective to move the piston `62 downwardly in relation to the housing 51. As the piston 62 moves downwardly, the treating agent in the lower enclosed space `66 will, of course, be forced therefrom by way of the lower ports 68 and into the annulus between the tool 50 and well casing below the expanded diverter S4.

When the piston 62 nears the lower limit of travel, a depending tubular probe 99 thereon will engage the inwardly-projecting ends of a plurality of inclined dogs 100 that are each carried in a housing recess 101 on a pivot pin 102 journalled to the housing 51 and have their outwardly-extending upper ends abutted against the lower face of the abutment 98. Biasing means, such as reverselybent springs 103, are provided to normally maintain the upper ends of the dogs 100 extended in the position shown in FIGURE 4B to support the abutment 98 against the force of the spring 96.

As seen in FIGURES 6A and 6B, once the lower end of the depending probe 99 from the piston 62 engages and passes the inwardly-projecting lower ends of the pivoted dogs 100, the dogs will be cammed to a generally erect position once the piston has reached the shoulder `57. Once the dogs 100 are pivoted into an upright position, the compressive force of the spring 96 will shift the sliding abutment 98 downwardly in relation to the sleeve member 73 until an inwardly-projecting shoulder 104 thereon halts further travel of the abutment. With the spring 96 confined between the shoulders 97 and 104 on the sleeve member 73, the spring 96 will, of course, no longer be effective to urge the sleeve member upwardly in relation to the housing 51 and only the force of the spring 95 will be maintaining the sleeve member in its elevated position. Although the elastomeric sleeve 69 is shown still extended in FIGURES 6A and 6B for purposes of illustrating that position, it will be recognized, of course, that once the abutment 98 is released, the spring strips 77 will begin expanding.

Accordingly, by selecting the spring 95 to have an effective spring force somewhat less than that required to bow the spring strips 77 outwardly against pressure forces acting downwardly on the diverter 54, once the spring 96 is immobilized between the shoulders 97 and 104, the forces tending to str-aighten the :bowed spring strips will be effective to return the sleeve member back to its initial position. It will 1be realized, however, that although the spring 95 must be appropriately selected to have a spring force which, when combined with that of the spring 96, will be sufficient to bow the spring strips 77 outwardly in the pre- 8 viously described manner, the spring 9S by itself will no be sufficiently strong to prevent relaxation of the spring strips once the spring 96 is immobilized. Thus, it will be appreciated that the function of the releasably-secured abutment 98 is to selectively enable and disable the spring by initially maintaining the spring 96 in a first position aiding the spring 95 and then, once the abutment is released, allowing the spring 96 to move to a second position in which the spring 95 is no longer effective to maintain the elastomeric sleeve 69 in its extended position.

Return of the slidable sleeve 73, will of course, carry the outer sleeve 83 back downwardly with little or no change in its position in relation to the slidable sleeve. It will also be noted from FIGURES 6A-6B that by providing ports in the upper end of the tubular probe 99, once the probe enters the bore 58 the remaining treating agent in the lower enclosed space 66 of the reservoir 53 will continue flowing therefrom to allow the piston 62 to move to a final position abutting the shoulder 57.

Those skilled on the art will, of course, recognize that several arrangements can be employed in the control section 55 to selectively detonate the explosive squib 88 from the surface without risking a premature actuation of the perforator (not shown) therebelow. In the exemplary tool 50 it is preferred, however, to employ selectively-actuated switching means to further and more positively prevent actuation of the perforator `before it is in position to correctly perforate the well bore.

Accordingly, as seen in FIGURES 4B and 5, a so-called single-pole double-throw switch 106 is mounted in the housing recess S6 and adapted for movement between a first switching position electrically connecting the explosive squib 88 to the conductor 60 and a second switching position electrically connecting the conductor 60 to the perfor-ating devices (not shown) in the perforator. To accomplish this, the switch 106 is provided with an actuator 107 that is normally engaged -with cam means, such as a flat 108, formed on a shaft 109 that is journalled at its opposite ends to the housing 51. A crank arm 110 secured to the shaft 109 and extending laterally therefrom is provided with a bifurcated end portion of clevis 111 that is movably coupled, as by a pin 112, to one end of an extension 113 dependingly secured from the lower end of the sleeve 73.

In this manner, so long as the slidable sleeve member 73 remains in the position shown in FIGURES 4A-4B, Only the explosive squib 88 will be electrically connected to the conductor 60. Then, as seen in FIGURES 6A-6B, once the sleeve 73 is released, the switch 106 will be operated to electrically connect the conductor 60 to the perforator (not shown).

To employ the tool 50 in the practice of the methods of the present invention, a suitable non-plugging liquid or some selected fluent treating substance of a similar or different vnat-ure is introduced into the lower enclosed space 66 of the reservoir 53 as by a filling port that is then closed by a plug 114 (FIGURE 4A). Typical treating agents that may be used are acid, propping agents containing particulate solids of sand, metal, glass, plastic and the like as well as various cleaning agents, and suitable temporary plugging agents such as gelled kerosene, gelled carbon tetrachloride, or such commercially available protective formulations as Black Magic sold by Oil Base, Inc. of Houston, Tex., or Plug Ban as sold by Humble Oil and Refining Co. of Houston, Tex. Any suitable agent can be used, of course, so long as it does not react adversely with formation materials and fluids and can =be removed from a perforation when it is produced. It should also be noted that as far as the tool 50 is concerned, improved results will be obtained where the treating substance has a lower density than that of the well control fluids so that once it is injected into the well |bore, the fluent substance will not tend to settle downwardly away from the diverter 54.

Once the reservoir 53 is lled and the other elements of the tool 50 are in their respective positions shown in FIGURES 4A-4B, the tool is suspended from a suitable cable (not shown) and lowered into a well bore to a position somewhat below the formation interval that is to be completed. It will be understood, of course, that a perforator and a depth-determining device Iare included with the tool 50 and are preferably arranged somewhat in the manner as the tool 10 depicted in FIGURES 1-3. Once the tool 50 is in position, electrical current is applied from a power source at the surface to the conductor 60 to detonate the explosive squib 88 and the tool 50 is raised toward the formation interval to be perforated.

When the squib 88 is detonated, the retaining sleeve 83 is moved upwardly by the spring 89 to free the balls 80 from the circumferential groove 82 and release the slidable sleeve member 73. Once the sleeve 73 is released, the combined spring force of the springs 95 and 96 will move the slidable sleeve member upwardly to extend the diverter 54 against the downwardly-acting pressure forces thereon. The outer sleeve 83 will have moved upwardly lrelative to the slidable sleeve 73 to bring the vports 93 and 94 into registration so that, once the slidable sleeve member has moved upwardly a distance sulicient to extend the diverter, the ports 93 and 94 will be in alignment with the housing ports 68.

While the diverter 54 is being extended, the tool 50 is still being moved upwardly so that once the ports 68, 93 and 94 are in alignment and the diverter is extended, the continued upward movement of the tool Will divert the Well bore fluids above the expanded elastomeric sleeve 69 through the upper housing ports 67 and into the upper reservoir space 65. As the well bore uids are diverted into the upper reservoir space 65, the piston 62 will be moved downwardly in relation to the housing 51 to discharge whatever uent substance there is in the lower reservoir space 66 through the lower housing ports 68 and into the well bore below the elastomeric sleeve 69.

It will be recognized that the treating agent being expelled into the well bore is moving into the annulus from which the well bore Huid entering the upper enclosed space 65 has just been displaced by the swabbing action of the diverter 54 resulting from the upward movement of the tool 50. Thus, there will be little or no chance that the treating agent will be dispersed into the well bore fluids. In this manner, the continued upward travel of the tool 0 will insure that a substantially homogeneous mass of the fluent substance will simultaneously envelop the lower portion of the tool 50 below the diverter 54. Accordingly, by the time that the perforator on the tool 50 has been moved into a position adjacent the formation interval to be perforated, the perforator will be completely enveloped by a homogeneous mass of the selected treating agent.

Once it is determined that the perforator is correctly positioned, electrical current is applied from a power source at the surface to the suspension cable to actuate the perforator. It will be recalled that the release of the retaining sleeve 83 will have actuated the switch 106 to connect the perforator to the conductor 60. Although the tool 50 can be halted before the perforator is actuated, it is preferred to continue moving the tool 50 upwardly as the perforator is actuated to insure that the last portion of the treating agent is expelled from the reservoir 53 a short time after the well bore is perforated. It will be appreciated, of course, that the position of the perforator in relation to the formation interval being completed will be known at all times by virtue of typical depth indicators at the surface whose accuracy is conlirmed by depth-correlation devices on the tool 50 such as the aforementioned casing-collar locator.

The effective volume of the reservoir 53 must, of course, be determined to insure that when the perforator is actuated, it is completely surrounded by the fluent substance. Moreover, where an enclosed retrievable carrier perforator is employed, the effective volume of the reservoir 53 should be sufficient to accommodate the volume of the fluent substance that will lill the carrier once it is perforated. In a typical arrangement of the tool 50 where an enclosed retrievable carrier perforator is used, the effective length of the lower enclosed space 66 will accordingly be in the order of about 1.5 to 2.0 times the length of the carrier. With relative proportions of this order, a continuing discharge of the uent substance will be obtained as the tool 50 is moved further upwardly after the perforator is actuated.

Once the piston 62 reaches the lower limit of its travel as determined by the shoulder 57, the tubular probe 99 thereon will have actuated the pvoted latch lingers 100 to release the movable abutment 98 and disable the spring 95. Once the spring is disabled, the elastomeric sleeve 69 will be restored to its retracted position and well bore tluids can again freely bypass the tool 50 as the tool is returned to the surface.

Turning now to FIGURE 7, a somewhat schematic view is shown of a second completion tool 200 which is also capable of practicing the methods of the present invention. As seen there, the tool 200 is suspended from a cable 201 in a cased well bore 202 just above an earth formation 203 which is to be completed in accordance with the principles of the present invention. The completion tool 200 preferably includes one or more typical centralizers 204 and 205 longitudinallyl spaced along the tool to maintain it centered in the well bore 202 as well as some means, such as a casing-collar locator 206, for determining the depth of the tool. A typical well perforator 207, such as an enclosed carrier 2018 with one or more perforating devices or shaped charges 209 therein, is coupled below the collar locator 206 and electrically connected to the suspension cable 201 in such a manner that the perforator can be selectively actuated upon command from the surface. The lower portion of the tool 200 is comprised of a selectively-actuated fluid diverter 210 and a reservoir 211 adapted to contain a uent substance for carrying out the particular completion operation.

As best seen in FIGURE 8, the fluid diverter 210 is preferably arranged in a similar fashion to the tool 50 previously described. Accordingly, as will be seen from a comparison of FIGURES LlA-4B with FIGURE 8, the fluid diverter 210 includes an elastomeric sleeve 212 that is releasab-ly secured in a relaxed position by a sleeve 213 slidably mounted around the tool body 214. The slidable sleeve 213 is held in an elevated position on the body 214 by one or more retaining balls 215 that are loosely disposed in lateral openings in the sleeve and are normally retained in a circumferential lgroove 216 by an outer sleeve 217 slidably mounted around the upper portion of the inner sleeve 213. An electrically-responsive release, such as an explosive squib 21S engaging a pivoted latch 219, is employed to prevent a spring 220 mounted between opposed shoulders on the sleeves 213 and 217 from moving the outer sleeve downwardly in relation to the inner sleeve until the squib is detonated upon command from the surface.

Once the outer sleeve 217 is released and has moved downwardly a sufficient distance to allow the balls 215 to move outwardly into longitudinal slots 221 in the outer sleeve, the inner sleeve 213 will be urged downwardly by a compression spring 222 retained between opposed shoulders 223 and 224 on the body 214 and inner sleeve respectively. Once the inner sleeve 213 begins moving downwardly in relation to the body 214, the spring force of the spring 222 will be sufficient to bow a plurality of circumferentially spaced, longitudinal spring strips 225 that are conned within the elastomeric sleeve 212 and have their opposite ends engaged with opposed shoulders 226 and 227 on the tool body 214 and inner sleeve 213 respectively. Thus, downward movement of the inner sleeve 213 will cause the elastomeric sleeve 212 to be expanded outwardly a sufficient distance to at least approach the inner surface of the well casing.

It will also be appreciated that the initial downward movement of the outer sleeve 217 by the spring 220 will bring one or more ports 228 in the sleeve into alignment with a corresponding number of ports 229 in the inner sleeve 213. Then, as the inner sleeve 213 is subsequently moved downwardly by the spring 222 and carries the outer sleeve 217 along with it, the ports 228 and 229 will be brought into registration with a plurality of ports 230 in the upper portion of the tool body 214. Once the ports 230 are uncovered, the upper end of a longitudinal bore 231 in the tool body 214 forming the upper end of the reservoir 211 is opened. Thus, once the elastomeric sleeve 212 is expanded and the ports 230 uncovered, downward movement of the tool 200 through the well bore 202 will force the well bore fluids 232 into a plurality of ports 233 in the upper end of the reservoir 211 to displace the treating agent 234 upwardly from the reservoir 211 and expel the agent through the ports 230 into the well bore 202 above the diverter 210. To insure that the treating agent 234 is displaced from the reservoir 211, a tubular member 235 is connected to the tool body 212 at the lower end of the bore 231 and extended downwardly therefrom to about the bottom of the reservoir.

Accordingly, to employ the tool 200 in practicing the methods of the present invention, a selected treating substance is disposed in the reservoir 211. Although this substance may be one of those previously described, it is preferred that this substance have a density somewhat greater than the density of the well bore lluids 232 to insure that the treating agent will remain as a homogeneous mass in the well bore 202 just above the expanded diverter 210.

Once the tool 200 has been brought into position just above the selected formation 203, the explosive squib 218 is detonated to expand the elastomeric sleeve 212 and open the ports 230. Thus, as the tool 200 is lowered further into the well bore 202, the well bore fluids 232 will be forced into the ports 233 to expel the treating agent 234 out of the ports 230 and envelop the annular clearance around the tool. Then, once the tool 200 has been lowered a sufcient distance to bring the perforator 207 into position opposite the formation 203, the perforator will be completely surrounded by the treating substance 234 and, upon detonation of the shaped charges 209, only the treating substance can enter the resulting perforations into the formation.

The tool 200 is simply raised to retrieve it to the surface following the actuation of the perforator 207. It will be recognized, of course, that the expanded diverter 210 Will not materially hamper retrieval of the tool 200 since the well bore fluids 232 will pass freely through the tool by way of the ports 230 and 233 since they are interconnected by the tubular extension 235 and the bore 231. Accordingly, the tool 200 is also capable of practicing the methods of the present invention.

Turning now to FIGURE 9, another completion tool 300 is shown in a cased well bore 301 and in position for practicing the methods of the present invention. The tool 300 is suspended from a cable 302 and maintained in the center of the well bore 301 by a typical centralizer 303 mounted on the upper portion of the tool. A casing-collar locator 304 is also preferably included with the tool 300 for providing indications at the surface of the position of the tool in relation to an earth formation, as at 305, to be completed.

The completion tool 300 is comprised of a reservoir section 306 having a fluid diverter 307 and an anchor 308 mounted thereon. A typical perforator 309 dependently secured below the reservoir section 306 is provided with one or more perforating devices, such as shaped charges 310, that may be selectively actuated upon command from the surface. If desired, another centralizer (not shown) similar to the centralizer 303 may be arranged on the perforator 309 to assure that the perforator is centrally located in the well bore 301.

The reservoir section 306 is comprised of an outer tubular housing 311 that is slidably telescoped around an elongated axial tubular member 312 dependently coupled, as by an adapter 313, to the upper portion of the tool 300 and connected, as by another adapter 314, to the upper end of the perforator 309. The upper portion of the tubular housing 311 is reduced in diameter, as at 315, and provided with a fluid seal, such as an O-ring 316, to slidably seal the upper end of the housing in relation to the depending tubular supporting member 312. The central portion of the tubular support 312 is enlarged in diameter, as at 317, and provided with a fluid seal 318 that is slidably engaged with the inner wall of the tubular housing 311 so as to define an enclosed space 319 within the housing between the reduced upper end 315 thereof and the enlarged portion of the depending support member.

A somewhat larger tubular member 320 is dependently secured to the enlarged central portion 317 of the elongated tubular support 312 and coaxially extended downwardly around the lower portion of the support to about the upper end of the perforator 309. A passage 321 through the enlarged-diameter portion 317 is adapted to provide fluid communication from the enclosed space 319 to the annular space 322 between the depending support 312 and the tubular member 320. selectively-operable valve means, such as an explosively-actuated valve 323, are provided to normally close the passage 321 and retain a treating agent 324 in the enclosed space 319 until the valve is actuated upon command from the surface. It will be appreciated that the axial passage 325 will permit suitable electrical conductors (not shown) to be passed from the upper portion of the tool 300 to the valve 323 and perforator 309.

The diverter 307 is comprised of one or more annular discs 326 of a thin, flexible material, such as may be cut from an elastomeric sheet, that are secured around the lower portion of the housing 311 and suitably sized to engage the inner walls of the cased well bore 301. It will be appreciated, however, that passage of the tool 300 through the well bore 301 will not be unduly hampered inasmuch as the well bore fluids 327 can readily pass around the llexible discs 326.

For reasons that will subsequently become apparent, the anchor 308 is adapted to lfrictionally engage the inner walls of the cased well bore 301 with a force greater than the restraining force provided by the centralizer 303 and any centralizer (not shown) mounted on the perforator 309. The restraining force provided by the anchor 308 is not so great, however, that the combined weight of the tool 300 will not carry the tool on downwardly into the well bore 301 as the cable 302 is unspooled from the surface. The anchor 308 is typically comprised of a number of so-called drag blocks or bowed spring strips 327 4arranged in the usual fashion.

Accordingly, once the enclosed space 319 is illled with the treating agent 324, it will lbe recognized that as the suspension cable 302 is unspooled at the surface, the tool 300 will descend into the well bore 301. As the tool 300 descends, the llexible elastomeric diverter 307 will retract as necessary to allow the well bore fluids 327 to pass around the tool. It will be appreciated that so long as the valve 323 remains closed, the fluent substance 324 in the reservoir space 319 will retain the housing 311 and support member 312 in the positions illustrated and prevent their relative movement. Once the collar locator 304 indicates that the tool 300 is so located with respect to the formation 305 that the lower end of the reservoir 306 is about even with the upper limit of the formation interval and the upper end of the perforator 309 is about even with the lower limit, the tool is halted.

Then, to practice the present invention, the tool 300 is selectively enabled by opening the explosiVely-actuated valve 323. Once the valve 323 is opened, upward movement of the suspension cable 302 will be effective to displace the treating agent 324 from the reservoir space 319 as the central support 312 and its enlarged portion 315 are moved upwardly in relation to the housing 311 which is now held stationary by the anchor 308. As the treating agent 324 is discharged through the passage 321 and annular clearance 322, the well liui'ds 327 will, of course, lill the `void below the enlarged portion 317 as it is moved upwardly into the now-stationary housing 311. Thus, the well fluids 327 in that portion of the well bore 301 below the elastomeric diverter 307 will be drawn upwardly into the reservoir housing7 311 as these fluids kare replaced by the treating agent 324. By extending the tubular member 320 to near the upper end of the perforator 309, the perforator will be progressively enveloped in a homogeneous mass of the fluent substance 324 as the perforator is brought upwardly into position. It will be recognized that by selecting the fluent substances 324 to have a lower density that that of the well liuids 327, the diverter 307 will keep the substances rfrom moving on up the well bore.

As Ia result, once the perforator 309 is at the upper limit of its travel (as determined by the collar locator and other typical depth-measuring devices at the surface), the movement of the cable 302 is halted. The perforator 309 is at this time completely surrounded by the fluent sulbstance 324 so that when the perforator is actuated, only the fluent substance can enter the resulting perforations (not shown). 'Ihe tool 300 is then simply withdrawn.

As described above, the tool 300 is arranged so that when the perforator 309 is at its upper limit of travel and is in position for actuation, the upper end of the penforator is somewhat below the lower end of the reservoir housing 311. It will be appreciated, however, that the tool 300 could also be so arranged that the perforator 309 would enter the lower open end of the reservoir housing 311 and be at least partially received by the reservoir 306 when the shaped charges 310 are detonated. This would, of course, require that lEhe housing 311 either be expendable or have appropriately located replaceable wall portions through which the perforating jets would pass. The advantage of this alternative arrangement would be that the overall length of this alternate tool would be reduced by la significant amount in relation to the length of the tool 300.

Accordingly, it will be appreciated that the present invention has provided new and improved metlhods by which a well bore can be perforated to allow only selected iiuent substances to enter the perforations. As described above, these methods can be conducted by any one of the several new and improved tools disclosed. It is quite apparent, therefore, that the present invention will enable la homogeneous mass of a selected substance to envelop a perforator before it is actuated so that only the substance will contact the formations when they are perforated. It should be realized, of course, that these fluiddisplacement tools are also suitable for use either alone or with other well tools aside from a perforator.

While particular procedures of the present invention have been shown and described, it is apparent that changes and modifications may ybe lmade without ydeparting from this invention in its broader aspects; and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. A method lfor completing an earth formation traversed yby a well bore containing liuids and comprising the steps of: suspending a tool including a perforator and a reservoir containing a liuent substance in a well bore proximate to an interval of said well bore that includes an earth formation to be completed; moving said tool into said well bore interval for simultaneously withdrawing iiuids from said well bore interval into said reservoir and discharging said liuent substance into said well bore interval to envelop said perforator with said iiuent sulbstance as it enters said well bore interval; and once said perforator is adjacent to said earth formation, actuating said perforator for perforating said earth fonmation to place said fluent substances in communication with such earth formations.

2. A method for completing an earth formation traversed by a well bore containing liuids and comprising the steps of: replacing well bore fluids occupying an interval of a well bore which traverses an earth formation with a fluent substance while simultaneously moving a perforator into said well `bore interval for enveloping said perforator with said liuent substance; and, actuating said perforator while it is enveloped in said iiuent substance for producing perforations into said earth [formation and placing said earth formation into communication with s'aid iiuent substance.

3. The method of claim 2 wherein said fluent substance is an `oil-soluble plugging agent adapted to isolate said perforations yfrom entry of well bore fluids.

4. The method of claim 2 wherein said fluent substance is composed of acidic constituents adapted to clean said perforations.

References Cited UNITED STATES PATENTS 2,693,856 11/1954 Allen 166-35 X 2,805,722 9/ 1957 Morgan et al 166-35 2,832,415 4/1958 Reistle 166-35 X 3,064,733 11/1962 Bourne 166-35 X 3,138,206 6/1964 Bruce et al 166 35 X 3,195,631 7/1965 Smith 166-35 3,361,204 1/1968 Howard et al 166-35 3,379,251 4/1968 Bohn 166-23 DAVID H. BROWN, Primary Examiner.

U.S. C1.X.R. 

